1. Field of the Invention
The present invention relates to a solar heating system, and more particularly to a system in which air and water are heated by the absorption of radiant solar energy.
2. Brief Description of the Prior Art
Solar heating systems currently available fall typically into one of two types, the first being considerably more complex and utilizing complicated components such as solar cells and heat exchange systems. The second type of solar hearing system uses a method of exposing water to radiant solar energy, the most common having a network of copper pipes on a roof surface, the pipes typically being coated black to absorb more heat. The water is thereafter used to heat a building structure (as through radiators) or for use as hot water.
While this second system is considerably less costly and complex, there are two significant problems involved. Firstly, in temperate climates where the ambient temperature may fall below freezing for a considerable period of time, some sort of anti-freezing agent must be added to the water to prevent it from freezing within the exposed pipes. This agent typically makes the water unsuitable for personal use and may even impart undesirable odors when the water is used for space heating. A second problem associated with this type of system is water leakage from the extensive network of pipes needed to expose a significant quantity of water to radiant solar energy. Frequent repairs and damage due to water leakage make this system somewhat less than desirable.
At present, most commercially available hot water heaters utilize either an electric heating coil or natural gas flames positioned near the bottom of a hot water heating tank in order to heat the water therein. The water which is provided to the hot water tank is normally supplied from the main water source of the particular building from an outside location. Therefore, the water is typically of ambient atmospheric temperature which, in many temperate climates, may be in the range of 40.degree. to 70.degree. F., depending upon the season. Therefore, if water is to be heated to a temperature of 130.degree. F. in the water heater, energy must be supplied sufficient to raise the temperature of the water 60.degree. to 90.degree. F.
It is known in the prior art to bubble hot gases through a body of water to raise the temperature thereof, however all such applications to date have apparently proceeded from utilizing products of combustion in order to generate the heat necessary to raise the water temperature. In U.S. Pat. No. 1,683,747, Wheeler, exhaust gases from an internal combustion engine are directed into a gas chamber, and then through a number of perforations into the body of water within the hot water tank. The gases pass upwardly in contact with the water and are thereafter discharged into the atmosphere.
U.S. Pat. No. 4,069,807, Hartig, shows a hot air heater wherein combustion products from the combustion of fuel oil or natural gas are forced through a water contacting device which cools the combustion gases and transfers heat to the water surrounding the water contacting device. The combustion gases and evaporated water are then transported through a heat exchanger where they are cooled and the evaporated water condensed and returned to the water contacting device. The combustion gases are vented to the atmosphere using a forced air system.
U.S. Pat. No. 2,536,608, Kemp, shows a liquid heater which uses products of combustion conducted through continuous or endless metal tubes as well as bubbling the combustion gases through a large volume of liquid in order to raise the temperature thereof.
U.S. Pat. No. 3,568,658, Brock, shows a burner can submerged in a water storage tank within which is combusted a mixture of gas and air. Water is admitted into the burner can from the tank and is heated therein, and then both the heated water and the combustion gases are injected back into the tank below the water level.
U.S. Pat. No. 3,371,789, Hensey, is not particularly relevant, but is cited as of interest for its aerating device.